Plastic foam material manufactured by expanding polymeric beads of polyethylene, polypropylene and polyurethane is used in a variety of situations. In some situations, finished products are formed by, for example, casting or molding the polymeric material in the presence of a blowing agent. In other cases, sheets or a block of foam are molded or otherwise formed that can be used for protective packaging or for additional processing by machining or other techniques that result in a desired product or product component. Advantageously, the process used to form the foam material and foam products can be controlled to establish a relatively wide density range. Further, the foam material and products exhibit a number of desirable properties such as relatively high energy absorption, resistance to denting or scarring caused by impact, light weight and resistance to chemicals and other substances. However, situations exist in which it is necessary or desirable to either coat the exterior of an item formed of expanded polymeric plastic foam with protective material to form a shell-like skin layer or to encase the foam with a relatively flexible sleeve formed of fabric that is coated or impregnated with protective material. Applying a protective coating to the exterior of an item formed of expanded polymeric plastic foam is somewhat disadvantageous in that several additional manufacturing steps are often required to obtain the desired protective coating. For example, it may be necessary or desirable to sequently coat the foam item with different types of material. Typically, each coat must be allowed to cure or dry prior to proceeding with additional steps of a manufacturing process. On the other hand, encasing an item formed of expanded polymeric plastic foam with a protective sleeve can result in problems from the standpoint of serviceability, appearance and performance unless the sleeve is placed under tension so that the sleeve is of a uniform, desired contour and shape.
Among the situations in which polymeric plastic foam material is either coated with protective material or is located within a protective sleeve is the fabrication of foam members commonly called collars that are affixed to the external surfaces of boat hulls to serve as stabilizers or fenders. By way of example, U.S. Pat. Nos. 5,282,436, 5,647,297 and 5,870,965 issued to Hansen, incorporated herein in their entirety by this reference, disclose high performance boats that are stabilized through the use of polymeric foam stabilizers. In the arrangement of Hansen, the foam stabilizers are mounted on the sides of the hull above the chine and extend from stern to bow. The foam stabilizers of the Hansen patents are not in contact with the water when the boat is at rest or is being operated at cruising speed. However, when the boat lists during high speed turns, the stabilizers enter the water and provide a righting moment that decreases list relative to what would otherwise be present. Although the stabilizers used in the Hansen patents are preferably formed from a foam such as closed cell polypropylene or polyethylene that does not absorb water and exhibits fair resistance to dents and chemicals, increased damage tolerance and tolerance to sunlight can be achieved by coating the exterior of the foam stabilizers with a protective material.
Examples of boat collars that employ sleeves that contain polymeric foam material include published U.S. patent application Ser. No. 20020096101 of Hansen and U.S. Pat. No. 6,371,040 to Hemphill et al., (each of which are hereby incorporated by reference). Although the Hansen patent application and the Hemphill et al. patent differ in several aspects, the arrangements disclosed in both of these references employ a cylindrical sleeve that is similar to conventional inflatable flotation collars and is only partially filled with expanded polymeric foam. More specifically, the polymeric foam used in the arrangement of Hemphill et al. is tubular, circumferentially surrounding and encasing an inflatable air bladder. In the Hansen patent application, polymeric foam inserts are employed that do not completely fill the sleeve with inflatable air bladders being located in regions of the sleeve that do not contain the foam inserts. In both the Hemphill et al. and Hansen arrangements, the air bladders are inflated to place the sleeve under tension to thereby provide a collar of desired shape, contour and firmness.
The solid foam boat collars described in the Hansen patents and the partially foam filled collars described in the Hemphill et al. patent and the Hansen patent application all function satisfactorily from the standpoint of stabilizing a boat and/or providing a fendering system. Nonetheless, a need exists for boat collars that incorporate the structural simplicity, ruggedness and durability of solid foam collars while simultaneously presenting advantages from the standpoint of ease of fabrication and the efficient manufacture and repair of foam collared boats.